The present invention relates to a vertebral fixing device for securing a rachidian vertebra to a rod, comprising a fixing body on the rod, a flexible strip for linking said vertebra with the fixing body and adjustable means for blocking the flexible strip on the fixing body.
It is particularly importantly applicable, although not exclusively applicable, in the field of the straightening of the spinal column of a patient having an abnormal curvature.
In this case, since the vertebrae are not correctly aligned relative to one another relative to the vertebral axis, they exhibit mutual inclinations.
In some places, the lateral edges of the vertebrae will therefore be, on one side, close to one another, and on the other side, distant from one another.
In order to straighten the assembly, it is known to reset to a substantially equivalent distance the lateral edges of the vertebrae on either side of the spinal column, by the use of rods linking together, either screws, that are inserted into the vertebrae themselves, or hooks, that are introduced along the rachidian channel.
Such devices do, however, present drawbacks.
The use of screws is first of all possible only if the vertebrae are in good condition and/or wide enough at the level of the fixing.
The use of hooks is very delicate since the operator must not touch the spinal cord for fear of paralyzing the patient.
To mitigate these drawbacks, there has been proposed (FR 02 09 317) a system that makes it possible to avoid the fixing screws or hooks.
The system comprises a flexible link for fixing the vertebra to a link part which is in turn fixed to the straightening rod.
Means for blocking the flexible link by reclosing the link part on the rod are provided. However, here again, this system does present drawbacks.
In practice it requires, on the one hand, an articulation of the link part so as to allow for the lateral insertion of the rod and of the flexible link, and, on the other hand, a fixing of the link to the part to allow for such blocking after the part has been reclosed on the rod.
Also known (EP 2 047 813) is a vertebral fixing device comprising a body for fixing a flexible strip on a rod, in the form of an articulated jaw.
Each branch of the jaw is provided with an orifice for the passage of one of the two strands of a loop of the strip, designed to be blocked at the bottom of said jaw by the rod once the jaw is reclosed and screwed.
The articulated device is fragile and does not allow for an easy adjustment of the flexible strip.
The same document describes another system, this time formed by a cylindrical part provided with a bottom orifice for the passage of the loop, and two top slots through which the free strands exit allowing the two strands to be wedged against the inner face of the cylinder by the use of a semi-cylindrical element, of a height substantially equal to the length of the part, and a screw for compressing said element onto the strands of the loop.
Such a system which clearly does not concern the securing of a vertebra on a cylindrical rod notably does not allow for easy placement, and notably requires a guiding tool.
Also known (WO 2009/013397) is a vertebral fixing device for a system for correcting abnormal curvatures of the vertebral column using a clamping collar consisting of a notched flexible strip passing into a part folded in two for fixing between its two branches a rod with opening for attaching the collar by notching. Such a device is difficult to adjust, and once tightened does not allow for the tightening to be repeated.